In the prior art, tendem axle suspension systems involve elevatable trailer bodies. It has been a problem to stabilize the loaded action of the wheels of the tandem axle system, such as shown in applicant's prior U.S. Pat. No. 3,837,665.
Additionally, the cantilever leaf springs, such as disclosed in said patent, tend to flex in the opposite direction when brakes are applied and with tandem axle elevatable trailer mechanisms of this general class, the loads normally carried by such trailers require that the trailers have brakes and tork reaction of the wheels when the brakes are applied tend to flex the suspension springs in the opposite direction and apply the load to only one leaf thereof.
As aforementioned, the suspension systems of the prior art tandem axle elevatable trailer structures have had a tendency to relex suspension forces of the springing system on one axle when bumps are encountered by the other one of the tandem axles; thus, maintaining level uniform suspension of the prior art systems when operating a tendem axle trailer over bumpy roads has caused some stability problems of the suspension systems.